Apparatus for moistening air



Nov. 23, 1965 P. GRAF ETAL APPARATUS FOR MOIS'IENING AIR Filed Dec. 51. 1962 INYENTORS Hans Bndmis m United States Patent 3,219,796 APPARATUS FOR MOISTENIN G AIR Paul Graf, Therwil, Switzerland, and Hans Badertscher,

Emil Frey-Strasse 183, Muuchenstein, Switzerland; said Graf assignor to said Badertscher Filed Dec. 31, 1962, Ser. No. 248,377 Claims priority, application Switzerland, Jan. 4, 1962,

7 Claims. (Cl. 219-285) The present invention broadly relates to improvements in apparatus for climatizing or conditioning air and, more specifically, has reference to an improved apparatus for adding moisture to air.

In heated rooms and in air-conditioning plants it is necessary, particularly in winter when the relatively dry outside air is introduced into rooms or spaces for purposes of ventilation or heating, to moisten the entering air current or the entered air. At the present time different apparatus and methods are utilized for moistening air. Thus, it is known to spray or atomize cold water out of a nozzle. Such can constitute a more or less useable method when the air is sufiiciently warm, which however, has the disadvantage when employing calcareous or lime containing water that the atomizing nozzles must be cleaned quite often. A further disadvantage is that the lime from the atomized water deposits itself everywhere as a thin film or layer in the ventilated room.

It is further known to the art to heat water in an open evaporation vessel by means of a heating rod, in a room containing air which is too dry or in a channel or duct serving as the supply line for heated air to a room to be ventilated, so that the water can evaporate or vaporize and can thereby moisten the air. The disadvantage of such an installation, among others, resides in the fact that, an open water vessel or container must be employed which soils very quickly, and in which during nonuse algae or other contaminations readily multiply. Furthermore, in such a device there is formed relatively quickly, pronounced calcareous deposits around the heating element, and special measures must be undertaken to prevent a burning out of the heating element during disruption or interruption of the water infeed.

With other electrically heatable water evaporators the hot water is processed in a boiler, from which the steam or vapor is conducted through a steam pipe to the static or flowing air. An exact adjustment of the generated vapor quantity, in this instance, is only possible via a control device for the rate of flow which, as is known, provides for a very poor exact dosing and, in addition, is readily subjected to contamination or fouling. If the air current or stream contains sufficient moisture then the boiler heater must be switchedoff, and it then takes a longer period of time until the production of steam or vapor is discontinued. Also, in this case, specific precautionary measures must be undertaken, so that when the infeed of water is absent there does not result any damage.

It is further known to the art to provide an evaporation vessel in which there are arranged two spatially separated electrodes, whereby the current flowing through the water heats this water. The generated water vapor can escape through a narrow opening provided in a cover member. The smaller such opening the larger is the pressure in the vapor compartment and the larger is the escape velocity of the vapor or steam jet. When all the water is evaporated then the current fiow between the two electrodes discontinues, since the air disposed therebetween acts as an insulation. However, since the generation of vapor is dependent upon the strength of the current flowing between the electrodes, the vapor pressure and therewith also the escape velocity of the vapor from the vessel considerably changes during operation. Additionally, such an installation must be continually replenished.

The steam or vapor generation apparatus for purposes of moistening air designed according to the teachings of the present invention, has as one of its primary objects to overcome all of these aforementioned disadvantages. The apparatus of the invention is manifested in the provision of a closed steam or vapor vessel containing two vertically arranged electrodes, the vapor compartment of which is connected with the air to be moistened by means of a vapor conduit, whereas the water compartment thereof is connected via a water conduit with a feed or supply conduit. The vapor conduit is provided at its end with a nozzle which produces an approximately constant pressure in the vapor compartment, whereas the mouth of the water conduit is located slightly beneath the lower edge of the electrode. The invention is further char acterized in that, the water conduit is directed upwardly and outside of the vessel, is connected with the feed conduit and is open at its upper end. Further, at a location above the upper electrode edge the water conduit is connected to an overflow conduit and is provided at its lowermost location with an outlet or discharge valve for emptying.

Accordingly, it is a further important object of the present invention to provide improved apparatus for applying moisture to air which is relatively simple in construction, highly reliable in operation, and relatively simple to service and clean.

A further important object of the present invention is the provision of improved apparatus for moistening air of the type comprising means for generating water vapor, and means for automatically rendering inoperative said vapor generating means when the moisture content of the air has reached a preset or adjustable valve.

Still a further important object of the invention is to provide improved apparatus for moistening air provided with means for generating water vapor, means for directing such water vapor to the air to be processed including means for producing an approximately constant pressure in a vapor compartment of said vapor generating means, and means for supplying water to said vapor generator means and emptying the latter when such is rendered inoperative.

A further important object of the present invention is to provide an improved apparatus for adding water vapor or moisture to an air current, wherein means are pro vided for regulating the water level affecting the heating capacity of electrode members for heating the water in dependence upon the vapor pressure prevailing in an evaporator vessel, such that a constant or approximately constant vapor stream escapes from said evaporation vessel, independently of the conductivity of the water and whether said electrode members are new or partially coated with a foreign material.

Still further objects and the entire scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description and specific example, while indicating a preferred embodiment of the invention, is given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

In the drawing:

FIGURE 1 schematically illustrates a preferred embodiment of apparatus for moistening air according to the present invention; and

FIGURE 2 illustrates a cross-sectional view through the evaporation vessel, taken along lines II -II of FIG- URE 1.

Referring now to the drawing, it is to be appreciated that the most important component of the entire installation is the evaporating vessel, generally designated by reference numeral 10. The evaporation vessel 10 can consist of a suitable non-conductive, refractory or heatresisting material, as for example a hard glass. In the illustrated embodiment, the vessel or container 10 is provided with a base member 1 and a cover member 2 which are pressed against a tubular jacket or casing S by means of a threaded shaft or spindle 4 provided with nut members 3, in a manner best shown in FIGURE 1. Additionally, heat-resisting sealing rings 6 are arranged at the respective ends 1a, 2a of the jacket member between the confronting faces of the base member 1 and cover member 2, to thereby provide a good sealing effect even when there results expansion or changes in length of the aforementioned parts by virtue of temperature variations.

A water conduit 7 piercingly extends through the base member 1 in fluid tight fashion, whereas in the cover member 2 there is arranged a vapor or steam conduit 8 and a water vapor-tight and heat-resisting lead-in duct or bushing 9 for the electrical conductors or lines 11 and 12. Naturally, it is also possible to arrange this lead-in supply means in the base member 1, so that the conductors 11 and 12 leading to both electrodes 13 and 14, as well as specifically the connecting points or junctions are not subjected to any high temperatures.

Each of the two electrodes 13 and 14 are formed by a vertically arranged cylindrical jacket or casing member preferably possessing a non-smooth surface, and in the present case consisting of a wire netting or gauze wire. The outer electrode 13 is approximately spanned at the region of the tubular jacket 5, whereas the inner electrode 14 is supported by individual wires or the like mounted to an insulating tube 15 enclosing or surrounding the threaded shaft 4. The insulating tube 15 can, for example, be formed of glass or a refractory or heat-resisting plastic or synthetic material.

As can best be seen from an inspection of FIGURE 1, the two electrodes 13 and 14 do not extend the entire height of the evaporation vessel 10, and there remains at the top as well as at the bottom of said vessel an electrode-free compartment a and 10b respectively. More specifically, these electrodes 13, 14 extend through the major portion of the height of the evaporation vessel 10, in other words through a distance which is greater than fifty-percent of such height. It will further be seen that the mouth 7:: of the water conduit 7 is located just below the lower edge of the electrodes that is, such that the vessel 10 can empty to just such an extent that the electrodes 13 and 14 are no longer wetted with water.

This water conduit 7 is directed externally of the vessel 10 in an upward direction and is provided at its upper and with a funnel member 7d, into which a water condensation conduit 16 discharges. At a convenient location on the water conduit 7 there is connected a feed or supply conduit 17. Furthermore, above the upper edges of the electrodes, that is at location 7b, there is connected an overflow conduit 18. The feed or supply conduit 17 is connected to the main water line or network (not shown) and contains a filter 20, an electric valve 21 which is closed when there is no current flow, and a nozzle member 19. At the lowest location of the water conduit 7, namely at position 70, there is connected a discharge conduit 22 which communicates with the overflow conduit 18. The discharge conduit 22 is provided with an outlet valve 23 of the electric valve type which is open when no current flows.

The vapor or steam conduit 8 is provided at its end with a nozzle member 8a out of which water vapor flows into the wide distributing pipe 24 arranged in an air channel or duct member 25. The distributing pipe 24- is provided with a plurality of holes or openings 24a and its end which is removed from the nozzle 8a is slightly inclined with respect thereto, so that in the event that water of condensation forms, it can reach such end and from there flow via the condensation pipe or conduit 16 into the funnel member 7d.

The electric circuit is just as simple as the mechanical construction. From the power or current supply network V there extends a pair of conductors or leads 11 and 12 t0 the two electrodes 13 and 14, respectively. The current flow though the two conductors 11 and 12 can be interrupted by a circuit breaker or cut-off switch 26. A signal lamp 27 bridges the two conductors 11 and 12 after the cut-off switch 26, whereby it is possible to ascertain at any time whether the switch 26 is open or closed. The conductor 11 is coupled with an ammeter 28 serving as a control for the current consumption. A ventilator, blower or fan 29, for generating an air current which is to be moistened in accordance with the apparatus of the invention, is further connected to the current supply network V. The ventilator or fan 29 can be switched-on and off by means of a circuit breaker or disconnecting switch 30.

At a convenient location in the path of the moistened air current, that is either in the channel or duct member 25 or in a room or space which will be climatized or conditioned by said moistened air current, there is arranged a moisture-dependent cut-01f switch 31. This cut-ofi or disconnecting switch 31 then opens an electric circuit when the moisture has reached or exceeds an adjustable value, and then again closes the electric circuit when the moisture again falls below the preset or adjusted value. The two electric valves 21 and 23 are connected in parallel to one another and to the current supply network V in such a manner that they are without current upon opening the cut-off switch 26 as well as by switching-off the fan 29, that is by opening the cut-off switch 30, as well as being without current when the moisture at the moisture-dependent cut-off switch 31 has reached the adjusted or preset value.

The mode of operation of the aforedescribed installation will now be considered. If it is desired to place the described installation into operation, then it is only necessary to close both of the switch members 26 and 30. By so doing, there is applied a voltage to the two electrodes 13 and 14, the fan 29 draws air, and the electric valve 21 is open and the electric valve 23 is closed. The water flows through the filter 20 arranged in the supply conduit 17 to the water conduit 7 with a flow velocity which is governed by the nozzle member 19. The bore of the nozzle member 19 is accommodated to the prevailing water pressure in such a manner that approximately 20% more water flows through the conduit than is required to be evaporated. The water then reaches the evaporation vessel 10 via the water conduit 7. As soon as the electrodes 13, 14 are wetted current then begins to flow between said electrodes, the water is heated, and there is formed steam or vapor which collects in the upper portion of the evaporation vessel 10, namely, in the vapor chamber or compartment 10a. The vapor escapes from the vapor compartment through the vapor conduit 8.

The quantity of steam or vapor which can be supplied to the air current is dependent upon the cross-section of the nozzle member 8a. Since not all of the water vapor which forms in the evaporation vessel 10 can immediately flow away, because of this nozzle 8a, there exists a vapor pressure in the vapor compartment 10a which downwardly presses the water and, in consequence thereof, displaces such water via the water conduit 7 through the overflow conduit 18. Consequently, the region or portion of the electrodes 13 and 14 which are wetted by the water becomes smaller and, as a result, the heating capacity and therewith the vapor generation capacity recedes until the pressure in the vapor compartment 10a corresponds to the pressure of the water column in the water conduit 7 plus the atmospheric pressure.

If, then, the heating capacity for maintaining the vapor pressure is too small then the water level in the vessel 10 again increases and there is obtained a balance or equilibrium, so that a constant vapor stream always flows through the nozzle member 8a, and indeed, independently of the fact Whether the conductivity of the water is somewhat larger or smaller and, also, independent of whether the electrodes 13, 14 are new or partially coated with lime. With new electrodes the water column will be very low; as soon as the lower part of the electrodes are calcified the water level or column will automatically rise until the layer of lime forming on the electrodes completely insulates such.

In order that a sufficient vapor pressure can also form then when almost the entire electrode surfaces are covered with an insulating lime layer, the connection or junction point of the overflow conduit 18 should be located about 46 cm. above the upper edges of the electrodes whereby the exact height must be determined in accordance with the desired vapor pressure as a function of the nozzle member 8a. It is here to be mentioned that the electrodes 13, 14 are preferably formed of a corrosion resistant metallic fabric, the mesh size or mesh aperture of which is so calculated that by heating and subsequent cooling the larger pieces of lime deposited on the metallic fabric in the form of lime particles, that is in the form of small cubes, grains or flakes may be blown-off the fabric.

As soon as the moisture in the space or room, where there is situated the moisture dependent cut-off switch 31, has reached its preset or adjusted value, said cut-off switch opens the current circuit which excites the electric valves 21 and 23, so that the water supply is shut-oft and the outlet or discharge valve 23 is opened, whereupon the evaporation vessel immediately empties until the mouth 7a of the water conduit 7 disposed in the water chamber 10b is reached. Dirt and lime particles are thus retained on the floor or base member 1 of the vessel 10. Since a small current load is sufiicient for exciting the electric valves 21, 23 it is not necessary to place any great requirements upon the moisture-dependent cut-oft switch 31. As soon as the electrodes 13 and 14 are no longer electrolytically connected with one another, current no longer flows through said electrodes, so that the heating operation is shut-off. By virtue of employing the electrolytic heater there is also attained the necessary security that, with an eventual interruption of the water infeed there cannot result any damage. As soon as the air current which is controlled by the cut-off switch 31 is again too dry, then the electric valves 21 and 23 are again excited, and the installation will admix with said air current a quantity of water vapor dependent upon the opening of the nozzle member 8a.

In order to service the installation, the vessel 10 provided with the two electrodes 13 and 14 must be cleaned from time to time. Advantageously, the vessel 10 and the electrodes 13 and 14 are so dimensioned that cleaning thereof is necessary only once a year, whereby maintenance costs may be kept at a minimum.

Having thus described the present invention, what is desired to be secured by United States Letters Patent is:

1. Apparatus for producing vapor for moistening air comprising a closed evaporation vessel, at least two electrode members spacedly and substantially vertically arranged in said evaporation vessel, means for connecting a source of electric current to said electrode members, said evaporation vessel including a vapor chamber and a water chamber, said electrode members being supported in said water chamber of said evaporation vessel, a vapor conduit operatively connecting said vapor chamher with the air to be moistened, a water supply conduit through which water continually flows during operation of the apparatus, a water conduit connected with said water supply conduit and operatively connecting said water chamber with said water supply conduit, said vapor conduit including nozzle means for achieving an approximately constant pressure in said vapor cham- '6 ber, said nozzle means being constructed to provide a vapor pressure in said vapor chamber sufiicient to maintain the water level in said evaporation vessel at all times beneath the upper edges of said electrode members when in relatively unsoiled condition, so that during operation of the apparatus only a portion of the electrode members are employed, said water conduit including a mouth portion located below the lower edges of said electrode members, said water conduit extending from said mouth portion externally of said evaporation vessel in an upward direction to a point at least above the upper edge of said electrode members with its top end being open to atmosphere, an overflow conduit directly connected to said water conduit at a point above the upper edges of said electrode members, and a discharge valve provided for said water conduit at a point below said lower edges of said electrode members.

2. Apparatus for producing vapor for moistening air comprising a closed evaporation vessel, at least two spaced vertically arranged electrode members disposed in said evaporation vessel, means for supplying a source of electric current to said electrode members, said evaporation vessel including a vapor chamber and a water chamber, said electrode members being supported in said water chamber of said evaporation vessel, a vapor conduit operatively connecting said vapor chamber with the air to be moistened, a water supply conduit through which water continually fiows during operation of the apparatus, a water conduit connected with said water supply conduit and operatively connecting said water chamber with said water supply conduit, said vapor conduit including nozzle means for producing an approximately constant pressure in said vapor chamber, said nozzle means being constructed to provide a vapor pressure in said vapor chamber sufficient to maintain the water level in said evaporation vessel at all times beneath the upper edges of said electrode members when in relatively unsoiled condition, so that during operation of the apparatus only a portion of the electrode members are employed, said electrode members extending through a major portion of the height of said evaporation vessel, said water conduit including a mouth portion located below the lower edges of said electrode members, said water conduit extending from said mouth portion externally of said evaporating vessel in an upward direction to a point at least above the upper edges of said electrode members with its top end being open to atmosphere, an overflow conduit directly connected to said water conduit at a point above the upper edges of said electrode members, and a discharge valve provided for said water conduit at a point below said lower edges of said electrode members.

3. Apparatus for producing vapor for moistening air comprising a closed evaporation vessel, at least two vertically arranged and spaced electrode members located in said evaporation vessel, means for connecting a source of electric current to said electrode members, said evaporation vessel including a vapor chamber and a water chamber, said electrode members being supported in said water chamber of said evaporation vessel, a vapor conduit operatively connecting said vapor chamber with the air to be moistened, a water supply conduit through which water continually flows during operation of the apparatus, a water conduit connected with said water supply conduit and operatively connecting said Water chamber with said water supply conduit, said vapor conduit being provided at one end with nozzle means for producing an approximately constant pressure in said vapor chamber, said water conduit including a mouth portion located in said water chamber below the lower edges of said electrode members, said water conduit extending from said mouth portion externally of said evaporation vessel in an upward direction to a point at least above the upper edges of said electrode members with its top end being open to atmosphere, an overflow conduit directly connected to said water conduit at a point above the upper edges of said electrode members, and a discharge valve connected to the lowermost location of said water conduit for emptying said evaporation vessel.

4. Apparatus for producing vapor for moistening air according to claim 3; wherein said water supply conduit is provided with a filter, a nozzle member and an electric valve which is closed when in a currentless state, said discharge valve for emptying said evaporation vessel being an electric valve which is open when in a currentless state, an electric circuit including a voltage source and switch means in circuit with and controlling the supply of current to said electrode members and said electric valves in such a manner that no current flows to said electric valves when said electric circuit to said electrode members is open via said switch means, and a moisture-dependent cut-off switch arranged in the path of the air to be moistened and electrically coupled to said electric circuit to interrupt current flow to both of said electric valves upon reaching a preset maximum moisture value.

5. Apparatus for producing vapor for moistening air according to claim 4; including a ventilator fan for generating an air current to be moistened coupled in said electric circuit to said voltage source, said switch means including a switch member in said electric circuit for switching on-and-otl said ventilator fan, said ventilator fan being positioned with respect to said vapor conduit such that the generated air current is contacted by vapor leaving said nozzle means, said electric valves being arranged in said electric circuit such that no current fiows to said electric valves when said switch member switches- 01? said ventilator fan.

6. Apparatus for producing vapor for moistening air according to claim 3; wherein said electrode members are formed of a metallic fabric constructed as a wire netting, the mesh size of which is so selected that the lime particles from the water deposited on the wire netting during heating and cooling thereof can be blownoff of said metallic fabric.

7. Apparatus for producing vapor for moistening air according to claim 3; wherein said vertically arranged electrode members extend less than, yet through a major portion, of the height of said evaporation vessel.

References Cited by the Examiner UNITED STATES PATENTS 1,461,840 7/1923 Vignon 219-201 2,180,445 11/1939 Vickery 219-294 2,236,359 3/1941 Armstrong. 2,347,490 4/1944 Legeman 219-272 X 2,478,569 8/1949 Cooper. 2,510,672 6/1950 Watson 219-292 2,562,184 7/1951 Grondahl 219-285 2,790,890 4/1957 Kasuga 219-287 FOREIGN PATENTS 586,132 12/1924 France.

RICHARD M. WOOD, Primary Examiner.

ANTHONY BARTIS, Examiner. 

1. APPARATUS FOR PRODUCING VAPOR FOR MOISTENING AIR COMPRISING A CLOSED EVAPORATIONS VESSEL, AT LEAST TWO ELECTRODE MEMBERS SPACEDLY AND SUBSTANTIALLY VERTICALLY ARRANGED IN SAID EVAPORATION VESSEL, MEANS FOR CONNECTING A SOURCE OF ELECTRIC CURRENT TO SAID ELECTRODE MEMBERS, SAID EVAPORATIONS VESSEL INCLUDING A VAPOR CHAMBER AND A WATER CHAMBER, SAID ELECTRODE MEMBERS BEING SUPPORTED IN SAID WATER CHAMBER OF SAID EVAPORATIONS VESSEL, A VAPOR CONDUIT OPERATIVELY CONNECTING SAID VAPOR CHAMBER WITH THE AIR TO BE MOISTENED, A WATER SUPPLY CONDUIT THROUGH WHICH WATER CONTINUALLY FLOWS DURING OPERATION OF THE APPARATUS, A WATER CONDUIT CONNECTED WITH SAID WATER SUPPLY CONDUIT AND OPERATIVELY CONNECTING SAID WATER CHAMBER WITH SAID WATER SUPPLY CONDUIT, SAID VAPOR CONDUIT INCLUDING NOZZLE MEANS FOR ACHIEVING AN APPROXIMATELY CONSTANT PRESSURE IN SAID VAPOR CHAMBER, SAID NOZZLE MEANS BEING CONSTRUCTED TO PROVIDE A VAPOR PRESSURE IN SAID VAPOR CHAMBER SUFFICIENT TO MAINTAIN THE WATER LEVEL IN SAID EVAPORATION VESSEL AT ALL TIMES BENEATH THE UPPER EDGES OF SAID ELECTRODES MEMBERS WHEN IN RELATIVELY UNSOILED CONDITION, SO THAT DURING OPERATION OF THE APPARATUS ONLY A PORTION OF THE ELECTRODE MEMBERS ARE EMPLOYED, SAID WATER CONDUIT INCLUDING A MOUTH PORTION LOCATED BELOW THE LOWER EDGES OF SAID ELECTRODE MEMBERS, SAID WATER CONDUIT EXTENDING FROM SAID MOUTH PORTION EXTENALLY OF SAID EVAPORATION VESSEL IN AN UPWARD DIRECTION TO A POINT AT LEAST ABOVE THE UPPER EDGE OF SAID ELECTRODE MEMBERS WITH IS TOP END BEING OPEN TO ATMOSPHERE, AN OVERFLOW CONDUIT DIRECTLY CONNECTED TO SAID WATER CONDUIT AT A POINT ABOVE THE UPPER EDGES OF SAID ELECTRODE MEMBERS, AND A DISCHARGE VALVE PROVIDED FOR SAID WATER CONDUIT AT A POINT BELOW SAID LOWER EDGES OF SAID ELECTRODE MEMBERS. 